| | Re: fish food
I think I replied to this thread, but my post seems to have disappeared.
I use the Walstad method, and I interpret her advice to mean "feed the fish generously, but don't leave rotting fish food on the bottom of the tank". I keep lots of detritivores in my tanks--snails, shrimp, catfish, etc.--so that no food remains uneaten for long.
Fish food is a source of nutrients for both fish and plants. It is a necessary input for the tank, just like light and water. What makes fish food safe as a fertilizer for plants is that it is "processed" by the animals; eaten, digested, and excreted in a form that can quickly be broken down by bacteria into compounds that feed plants but are safe for fish. It is not like dosing synthetic fertilizers, which are used directly by the plants.